How to check if a character is alphanumeric in Java with if-else
Overview
Without any inbuilt method, we can check if a given character is alphanumeric or not. An alphanumeric character is a character that is either a number or an alphabet. The logic to find out if a character is alphanumeric is listed below:
- Is the character greater than or equal to
'0'and less than or equal to9? - Or is the character greater than or equal to
aand less than or equal toz? - Or is the character greater than or equal to
Aand less than or equal toZ?
We can see if a character is an alphanumeric character with these given conditions above.
Syntax
if ((character >= '0' && character <= '9') || (character >= 'a' && character <= 'z') || (character >= 'A' && character <= 'Z')){// character is alphanumeric}else{// character is not alphanumeric}
Syntax to check if a character is alphanumeric in Java without an inbuilt method
Parameters
character: This is the character we want to check if it is alphanumeric or not.
Example
class HelloWorld {// create function to check if alphanumericstatic void checkIfAlphanumeric(char character){if ((character >= '0' & character <= '9') || (character >= 'a' && character <= 'z') || (character >= 'A' && character <= 'Z')){System.out.println(character +" is alphanumeric");}else{System.out.println(character +" is not alphanumeric");}}public static void main( String args[] ) {// check if some characters are alphanumericcheckIfAlphanumeric('e');checkIfAlphanumeric('1');checkIfAlphanumeric('r');checkIfAlphanumeric('%');checkIfAlphanumeric(',');}}
Explanation
- Line 3: We create a function to check if a character is alphanumeric. It takes a character as a parameter and applies the condition discussed above.
- Lines 12–16: We check if some characters are alphanumeric with the function we created.